1. Field of the Invention
This invention relates to a packaged article and, more particularly, it relates to a packaged article to be suitable used for storing infusion that contains oxygen degradable substances such as amino acids with the passage of time under stable conditions.
2. Description of the Related Art
Transfusion, or drip transfusion, is a therapeutic technique to be used for administering a large quantity of liquid medicine to the patient through a vein. Infusions used for transfusion typically include nutrient solutions designed to cause nutrients to be taken into the patient in a non-intestinal way, electrolyte solutions designed to cure the dehydration and improve the humor of the patient and plasma booster solutions designed to maintain the blood pressure of the patient during a surgical operation.
Of these infusions, sugar solutions, amino acid solutions, fat emulsions are among the most popular ones.
Any of these infusions are used for improving the physical strength of the patient during and after the surgical operation and often show a remarkable effect particularly when the patient is not capable of ingesting foods per-intestine.
Amino acid solutions used for transfusion normally contain essential amino acids and quasi-essential amino acids as well as non-essential amino acids prescribed to show a composition that facilitates intake by the human body and can be categorized into several groups including one based on the amino acids found in human milk. Nutrient solutions prepared by adding one or more than one sugar alcohols such as xylitol or electrolytes to amino acid solutions are also popularly used.
A fat emulsion is in fact an O/W type emulsion prepared by adding a physically permissible emulsifier to one or more than one kinds of vegetable oil such as soybean oil. Therefore, it normally contains as nutritious ingredients palmitic acid, stearic acid and other saturated fatty acids as well as oleic acid, linoleic acid, linolenic acid and other unsaturated fatty acids. Fat emulsions additionally containing unsaturated fatty acids that are important but not found in vegetable oils such as eicosapentaenoic acid and docosahexaenoic acid are also gaining popularity.
Infusions as described above are conventionally contained in medical containers such as vials, synthetic resin bottles and synthetic resin film bags for ease of distribution and use.
While each of these containers has its own advantages and disadvantages, a synthetic resin film bag or a synthetic resin bottle may be recommendable as it is less expensive and practically free from damages during transportation.
Synthetic resin materials to be used for infusion containers need to meet the following requirements;
(1) not permeable to liquid,
(2) capable of completely blocking invasion of micro-organisms from outside,
(3) having sufficient mechanical strength if used for infusion containers,
(4) sufficiently heat-resistive if heated for sterilization and
(5) free from problems due to exudation.
Polyvinyl chloride and crosslinked ethylene-vinyl acetate copolymer resin (crosslinked EVA resin) are among popularly used synthetic resin materials that meet the above requirements.
Solutions containing amino acids, electrolytes and/or sugar alcohols and fat emulsions as described above are accompanied by a problem of being colored brown (hereinafter referred to as browning) during storage to lose totally or partly their commercial values.
Browning occurs when any of the ingredients of a solution are chemically affected by oxygen existing in the solution. Therefore, browning is not only a problem of appearance but a problem of reducing the concentration of amino acids and fats in the solution and producing chemicals that may adversely affect the human body. Browning can also be observed in fat emulsions, where unsaturated fatty acids contained in them are decomposed with time to produce peroxides and thereafter aldehydes, ketones or carboxylic acids, giving rise to problems such as reduction in the pH level.
The problem of browning becomes particularly remarkable when synthetic resin bottles or bags are used for containers. This is because synthetic resins used as materials for bottles and bags such as vinylchloride resins and cross linked EVA resins possess a certain degree of gas permeability and therefore oxygen molecules in air can get into the infusions contained in the bottles and bags to increase the concentration of dissolved oxygen. This is a phenomenon that vials are exempted from.
In an attempt to avoid the problem of gas permeability, there has been proposed a hardly gas permeable sack prepared by laying a pair of polyester resin sheets together, vapor depositing aluminum on the opposite surfaces and heat-sealing the periphery of the sheets by means of a hot-melt type adhesive so that it may hermetically enclose a synthetic resin bottle or bag.
However, a sack as described above is accompanied by certain problems. Firstly, it is inconvenient for storing because it is deformable. Secondly, it can be flattened when placed under a heavy load during storage or transportation and adversely affect the item contained in it. Thirdly, the item contained in it can become shaky and displaced during haulage and eventually damage the sealed area of the sheets to produce pin holes or separation of sheets, which by turn ruin the airtightness of the sack.